nds32/ftrace: Support dynamic function tracer

This patch contains the implementation of dynamic function tracer.
The mcount call is composed of three instructions, so there are three
nop for enough placeholder.

Signed-off-by: Zong Li <zong@andestech.com>
Acked-by: Greentime Hu <greentime@andestech.com>
Signed-off-by: Greentime Hu <greentime@andestech.com>

diff --git a/arch/nds32/Kconfig b/arch/nds32/Kconfig
index 48d92171ea20e3e9924b18e023ccbed0c93e9c32..7068f341133d7eb038bb94a9953a3b9946d9bf51 100644 (file)
--- a/arch/nds32/Kconfig
+++ b/arch/nds32/Kconfig
@@ -43,6 +43,7 @@ config NDS32
        select HAVE_FUNCTION_TRACER
        select HAVE_FUNCTION_GRAPH_TRACER
        select HAVE_FTRACE_MCOUNT_RECORD
+       select HAVE_DYNAMIC_FTRACE
        help
          Andes(nds32) Linux support.
 

diff --git a/arch/nds32/include/asm/ftrace.h b/arch/nds32/include/asm/ftrace.h
index bac7657f576a9ba9af4f4c127316a56a5ebd3fc5..2f96cc96aa35c0dd0795674068bf414e7a08ab2e 100644 (file)
--- a/arch/nds32/include/asm/ftrace.h
+++ b/arch/nds32/include/asm/ftrace.h
@@ -15,6 +15,32 @@
 
 extern void _mcount(unsigned long parent_ip);
 
+#ifdef CONFIG_DYNAMIC_FTRACE
+
+#define FTRACE_ADDR ((unsigned long)_ftrace_caller)
+
+#ifdef __NDS32_EL__
+#define INSN_NOP               0x09000040
+#define INSN_SIZE(insn)                (((insn & 0x00000080) == 0) ? 4 : 2)
+#define IS_SETHI(insn)         ((insn & 0x000000fe) == 0x00000046)
+#define ENDIAN_CONVERT(insn)   be32_to_cpu(insn)
+#else /* __NDS32_EB__ */
+#define INSN_NOP               0x40000009
+#define INSN_SIZE(insn)                (((insn & 0x80000000) == 0) ? 4 : 2)
+#define IS_SETHI(insn)         ((insn & 0xfe000000) == 0x46000000)
+#define ENDIAN_CONVERT(insn)   (insn)
+#endif
+
+extern void _ftrace_caller(unsigned long parent_ip);
+static inline unsigned long ftrace_call_adjust(unsigned long addr)
+{
+       return addr;
+}
+struct dyn_arch_ftrace {
+};
+
+#endif /* CONFIG_DYNAMIC_FTRACE */
+
 #endif /* CONFIG_FUNCTION_TRACER */
 
 #endif /* __ASM_NDS32_FTRACE_H */

diff --git a/arch/nds32/kernel/ftrace.c b/arch/nds32/kernel/ftrace.c
index 707fce76522e69fc685c565fe5e61e4ac5aaf7eb..3ca676b75d976d7099d18b61fb6c86ed9bb74f27 100644 (file)
--- a/arch/nds32/kernel/ftrace.c
+++ b/arch/nds32/kernel/ftrace.c
@@ -4,6 +4,7 @@
 #include <linux/uaccess.h>
 #include <asm/cacheflush.h>
 
+#ifndef CONFIG_DYNAMIC_FTRACE
 extern void (*ftrace_trace_function)(unsigned long, unsigned long,
                                     struct ftrace_ops*, struct pt_regs*);
 extern int ftrace_graph_entry_stub(struct ftrace_graph_ent *trace);
@@ -35,6 +36,168 @@ noinline void _mcount(unsigned long parent_ip)
 }
 EXPORT_SYMBOL(_mcount);
 
+#else /* CONFIG_DYNAMIC_FTRACE */
+
+noinline void __naked ftrace_stub(unsigned long ip, unsigned long parent_ip,
+                                 struct ftrace_ops *op, struct pt_regs *regs)
+{
+       __asm__ ("");  /* avoid to optimize as pure function */
+}
+
+noinline void __naked _mcount(unsigned long parent_ip)
+{
+       __asm__ ("");  /* avoid to optimize as pure function */
+}
+EXPORT_SYMBOL(_mcount);
+
+#define XSTR(s) STR(s)
+#define STR(s) #s
+void _ftrace_caller(unsigned long parent_ip)
+{
+       /* save all state needed by the compiler prologue */
+
+       /*
+        * prepare arguments for real tracing function
+        * first  arg : __builtin_return_address(0) - MCOUNT_INSN_SIZE
+        * second arg : parent_ip
+        */
+       __asm__ __volatile__ (
+               "move $r1, %0                              \n\t"
+               "addi $r0, %1, #-" XSTR(MCOUNT_INSN_SIZE) "\n\t"
+               :
+               : "r" (parent_ip), "r" (__builtin_return_address(0)));
+
+       /* a placeholder for the call to a real tracing function */
+       __asm__ __volatile__ (
+               "ftrace_call:           \n\t"
+               "nop                    \n\t"
+               "nop                    \n\t"
+               "nop                    \n\t");
+
+       /* restore all state needed by the compiler epilogue */
+}
+
+int __init ftrace_dyn_arch_init(void)
+{
+       return 0;
+}
+
+int ftrace_arch_code_modify_prepare(void)
+{
+       set_all_modules_text_rw();
+       return 0;
+}
+
+int ftrace_arch_code_modify_post_process(void)
+{
+       set_all_modules_text_ro();
+       return 0;
+}
+
+static unsigned long gen_sethi_insn(unsigned long addr)
+{
+       unsigned long opcode = 0x46000000;
+       unsigned long imm = addr >> 12;
+       unsigned long rt_num = 0xf << 20;
+
+       return ENDIAN_CONVERT(opcode | rt_num | imm);
+}
+
+static unsigned long gen_ori_insn(unsigned long addr)
+{
+       unsigned long opcode = 0x58000000;
+       unsigned long imm = addr & 0x0000fff;
+       unsigned long rt_num = 0xf << 20;
+       unsigned long ra_num = 0xf << 15;
+
+       return ENDIAN_CONVERT(opcode | rt_num | ra_num | imm);
+}
+
+static unsigned long gen_jral_insn(unsigned long addr)
+{
+       unsigned long opcode = 0x4a000001;
+       unsigned long rt_num = 0x1e << 20;
+       unsigned long rb_num = 0xf << 10;
+
+       return ENDIAN_CONVERT(opcode | rt_num | rb_num);
+}
+
+static void ftrace_gen_call_insn(unsigned long *call_insns,
+                                unsigned long addr)
+{
+       call_insns[0] = gen_sethi_insn(addr); /* sethi $r15, imm20u       */
+       call_insns[1] = gen_ori_insn(addr);   /* ori   $r15, $r15, imm15u */
+       call_insns[2] = gen_jral_insn(addr);  /* jral  $lp,  $r15         */
+}
+
+static int __ftrace_modify_code(unsigned long pc, unsigned long *old_insn,
+                               unsigned long *new_insn, bool validate)
+{
+       unsigned long orig_insn[3];
+
+       if (validate) {
+               if (probe_kernel_read(orig_insn, (void *)pc, MCOUNT_INSN_SIZE))
+                       return -EFAULT;
+               if (memcmp(orig_insn, old_insn, MCOUNT_INSN_SIZE))
+                       return -EINVAL;
+       }
+
+       if (probe_kernel_write((void *)pc, new_insn, MCOUNT_INSN_SIZE))
+               return -EPERM;
+
+       return 0;
+}
+
+static int ftrace_modify_code(unsigned long pc, unsigned long *old_insn,
+                             unsigned long *new_insn, bool validate)
+{
+       int ret;
+
+       ret = __ftrace_modify_code(pc, old_insn, new_insn, validate);
+       if (ret)
+               return ret;
+
+       flush_icache_range(pc, pc + MCOUNT_INSN_SIZE);
+
+       return ret;
+}
+
+int ftrace_update_ftrace_func(ftrace_func_t func)
+{
+       unsigned long pc = (unsigned long)&ftrace_call;
+       unsigned long old_insn[3] = {INSN_NOP, INSN_NOP, INSN_NOP};
+       unsigned long new_insn[3] = {INSN_NOP, INSN_NOP, INSN_NOP};
+
+       if (func != ftrace_stub)
+               ftrace_gen_call_insn(new_insn, (unsigned long)func);
+
+       return ftrace_modify_code(pc, old_insn, new_insn, false);
+}
+
+int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
+{
+       unsigned long pc = rec->ip;
+       unsigned long nop_insn[3] = {INSN_NOP, INSN_NOP, INSN_NOP};
+       unsigned long call_insn[3] = {INSN_NOP, INSN_NOP, INSN_NOP};
+
+       ftrace_gen_call_insn(call_insn, addr);
+
+       return ftrace_modify_code(pc, nop_insn, call_insn, true);
+}
+
+int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec,
+                   unsigned long addr)
+{
+       unsigned long pc = rec->ip;
+       unsigned long nop_insn[3] = {INSN_NOP, INSN_NOP, INSN_NOP};
+       unsigned long call_insn[3] = {INSN_NOP, INSN_NOP, INSN_NOP};
+
+       ftrace_gen_call_insn(call_insn, addr);
+
+       return ftrace_modify_code(pc, call_insn, nop_insn, true);
+}
+#endif /* CONFIG_DYNAMIC_FTRACE */
+
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
                           unsigned long frame_pointer)
@@ -94,4 +257,5 @@ void __naked return_to_handler(void)
                /* restore state nedded by the ABI  */
                "lmw.bim $r0,[$sp],$r1,#0x0  \n\t");
 }
+
 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */